Rail bond



A. L. LE

RAIL BOND Feb. 25; 1936.

Filed Aug. 30, 1953 sv /AVVII VX d M MM Patented Feb. 25, 1936 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to a rail bond.

The object of the invention is to provide simple means which may be readily applied, without welding or other mode of permanent attachment, to form an electrical connection of good conductivity between adjacent rails.

For railways in which electricity is the motive power, it has been customary to weld lengths of copper bar or wire to adjacent rail terminals, to provide the bond or interconnecting conductor for the lengths of rail. This practice is laborious, and prevents the re-rolling of rails after the rails have become worn, since the bonds are per manently fixed in position and must be cut away from the rail for removal. In mining practice, so much difi'iculty is experienced in welding copper bonds to adjacent rails, and the bonds are so frequently destroyed by derailment of the cars, with consequent cutting of the bonds by the car wheels, that many lengths of track in mines remain unbonded. This results in lack of proper electrical connection between rails, and frequently results in an arcing between rails, which is dangerous under the existing conditions. It also results in energy loss, overheating of equipment by operation at low voltage with consequent damage to the equipment, and loss of efiiciency in the operation of equipment due to power loss.

To explain some of the disadvantages of welding bonds to track used in coal mines, and similar mines, there is an explosion danger from the ignition of gases, by the welding operation, since welding cannot be performed in closed chambers. There is a resulting danger from the welding equipment due to inadequate grounding through the rails. Fire, and explosion, may result from leaving gobs of glowingmetal, heated in the welding operation, beside the track.

Electrical welding, aside from fire and explosion hazards, is an inherently dangerous operation, and is particularly so when performed by the high voltage machines used in mine weldmg.

The difiiculty in making a mechanical bond for electrical conductivity between adjacent rails is found in the tendency for such mechanical connections to oxidize under the conditions existing in coal mines and other mines where sulphur or sulphates are present. It has been found that this tendency to oxidation exists even though the material of a mechanically applied rail bond be of bronze, and that the oxidizing tendency destroys the electrical connection provided by the bonds with relatively great rapidity. My mechanical rail bond is so arranged that the region of contact between the rail and the bond itself is subjected to such pressure that oxides cannot be present to impair the direct contact of 5 metal to metal.

In the accompanying drawing, Fig. I is a side elevation showing two adjacent rails bonded in accordance with my invention; Fig. II is a crosssectional view through one rail and the bond 1 taken on the line II, II of Fig. I; Fig. III is a horizontal sectional view through the bonded rails and my rail bond taken on the line III, III of Fig. I; and Fig. IV isa front elevation of a U-bolt of modified form. 5

In the drawing, reference letter A designates both of the rails between which electrical connection is made, and reference letter B designates the fish plates or angle bars used for mechanical interconnection of the rails. As is :0 usual, the fish plates or angle bars B are attached to the rails A by means of bolts 3 and nuts 4, the shanks of the bolts 3 extending through matching openings 5 in the angle bars and 6 in the rails. It is to be understood that 25 my bonding structure is separate from and additional to the mechanical interconnection of the rails.

My bonding element comprises a U-bolt l, which has an elongated bight la and shank por- 30 tions lb. Shank portions lb of the U-bolt pass through matching openings 8 and 9 in the two angle bars B, and aligned openings In in the Web I I of each of the rails A. Each of the shank portions lb of the U-bolt carries a nut l2 having 35 a tapered portion 12a presented toward the rail.

It is to be noted as a matter of importance that the rail openings H, through which the shank portions lb of the U-bolt pass, are of a diameter appreciably greater than the diameter of the 40 bolt shanks. Also the openings 9 in that one of the angle bars B in which the nuts I2 lie are of such extent that the nuts may lie freely therein, without contacting the walls of the openings.

The procedure in electrically bonding adja- 45 cent rails by my mechanical rail bond comprises the positioning of one angle bar B to lap the ends of the abutting rails. This angle bar is the one which lies adjacent the bight la of the U-bolt. The shank portions lb of the U-bolt are then inserted through the openings 8 in this angle bar, and the openings ID in the webs H of rails A. Desirably in making this assembly, a stiff curved spring member 13, provided with notches M to embrace the shank portions of the U-bolt, is

, pelted nuts; This" compensates for-loosening positioned with its convex side against the outer face of the angle bar. When the connection has been made in the manner to be described, this spring, being distorted by that action, exerts a constant, effective forcetending to maintain the close electrical contact between the rails and the bond elements in contact therewith. With the parts in the position described, nuts I! are applied to the shank portion lb of the U-bolt, and are tightened down against webs, II of the rails. h, engaging the angle bar B to the rail, and straightening spring 53 as it lies against the outer face of the angle bar.

It has been noted that the openings In in rail webs II are of a diameter 'materially greater;

than the diameter of the shank portions 1b of.

the U-bolt; Tightening progression of the nuts l2, therefore, causes their tapered. portions Illa toenter these openings l9, and te have with the edges of the openings a line contact Great pressure maybe exerted upon the nuts t2 and the contact area C, between; the tapered portions ma, of the nuts, and the edges'of; the webopeningsbeing restricted, theunit pressure ,in', this restricted area. is increased, and can be madevery great.

As an example if the nut 12. be'provided-with a tenidegree taper and, a one thousand pounds pressure be applied to the-nut, the pressure in; the" 7 contact area is onethousand times the cosecant 'of ten degrees, which is 5.7588. The effective pressure is, therefore, '57588 pounds. Assuming that the area of contact line C is 0.3 square inch,

the unit pressure in the'contact area. is equalto- 5758.8 divided by 0.3,,or 19,19,6-pounds per square" inch. An: increase in contact area, due to increased nut diameter, is: compensated, for by in creaseinapplied pressure. 7 e

, This'pressure exceeds greatly the resistance of oxides to crushing, and, therefore, any" oxidesinitially present at the, line of contact are forced from thisline, sothat a true=metal-t0-metalcontact: is-rprovided This close conducting contact is maintained, sinceunder the pressure which is present nooxides may remain in; the limited area.

of: contact. The high pressureiis maintained: by

spring l3, which" has, been distorted'inthe-initial. tightening. The stiffness of this spring !3 issuch' 1 that. it tends to exert a reacting pressure: equal to theaacting pressure longitudinally of the ta:-

tendencies rrfi irrwr ear or oxidation of the-parts V r V 7 With electrical contact-thus made, thesecondangle bar Bqis placed-in position,rwith the openingsis therein embracing the more extendedregions of nuts 12;. .Thissecondangle-bar is secured in" the assembly by means of the straight" bolts 3, and-nuts 4. It is tobe understood that J neither of the-angle: bars B performs any "electrical'function in the bonding of the rails, because theiclose" electrical contact is maintained at the contact areas C'between, the rail webs l'! and the nuts: i2. V

A-(detail of relatively great importance resides inthe-fact that the nuts l2 are heat treated, or

formedin the'tapered face of the'nut woulolde- When the tapered por- 7 stroy the take-up efiect" resulting from the taper, and would prevent the progressive take-upproducing a clean pressure contact. 7

The entire assembly may, if desired, be made of a corrosion-resisting material, or various suitable 5 1 between: the rail: bond and the rail itself exists .is of primary importance in effecting and maintaining adequate conductivity between adjacent 2o rails. ,7 s

The modification shown in Figure IV; of. the drawing is'in the U-bolt, and the purpose of the 'modi'fication is to compensate for expansion and contraction of bonded rails which are subject to; 25, marked temperature changes. a This modification is of-particular importance in connection with my general structure, in which the nuts 816E111 gaged-to-the rails under such high pressure that slippage cannot occur:

Thebight-I-fiof thismodified U-bolt. is formed with double curvature in the regions l6, sothata. certain resiliency is provided longitudinally of the bight. I have found that such structure-pro videsadequate compensation for expansion and contraction of adjacent rails under severe variations in? atmospheric temperature.

It may be noted that, with my mechamcal bonding, the-operation; of bonding is performed. simultaneously with the laying of the track,. while; welded bonds are made subsequently bonding is frequently negected.

Iclaim as'my invention: 7 I a s 1. In: a; conducting assembly for electrical current flow from rail torail, the'combination of 455; twoabutting-railshaving each an opening-in thev web thereof. adjacent the end of the rail, a-conducting U-bolt'having a, bightspanning the in-- terval between the web openings of adjacent;

; rails: and-shanks extendedthrough said openings, a. nut on eachof saidishanksi in the reg-ionwhich isprojected. through the web opening of a rail, I a taperedrail-contacting portion on each nut terminally; of a cross-sectional areato enter the web opening of the rail contacted by it, the nuts 5 7 being ofa conductive metal which is-of, ahardness suificiently greater than the hardness ofthe railto cause deformation of the rail, metal ratherthan deformation of the'nut metal when the-nuts 1 Q V are forced at high pressure into contact with (50 the wall of the web opening, and resilient means exerting a constant force adequate to. maintain a highpressure contact between the nuts and the rails.

- 2. In a rail joint comprising a conductive assembly for electrical. current between steel rails,

the combination of a conducting UJ-bolt having a bight adapted to spanthe interval between web openingsini adjacent rails to-be bonded electrically each to each and shanks adapted to pass through web openings in adjacent rails the interval between: which web openings'is spanneds' by'the bight of the U-bolt, tapered nuts on the, shanks of the U-bclt and adaptedto enter web openings in rails. bonded and: to contact the web walls surrounding said openings, and a bow spring lying between the shanks of the U-bolt of sufficient stiffness continuously to exert a pressure reactive to pressure exerted by the nuts exceeding the crushing resistance of iron oxides which may form on the rails bonded, said nuts being of a hardness exceeding that of steel rails as used in railway tracks, whereby the nuts are capable of enduring without deformation contact with the rails bonded under pressure adequate to exceed the crushing resistance of iron oxides.

3. In a rail joint comprising a conductive assembly for electrical current between steel rails, the combination of a conducting U-bclt having a bight adapted to span the interval between web openings in adjacent rails to be bonded electrically each to each and shanks adapted to pass through web openings in adjacent rails the interval between which web openings is spanned by the bight of the U-bolt, tapered nuts on the shanks of the U-bolt and adapted to enter web openings in rails bonded and to contact the web walls surrounding said openings, and resilient means lying between the shanks of the U-bolt of sufiicient stiffness continuously to exert a. pressure reactive to pressure exerted by the nuts exceeding the crushing resistance of iron oxides which may form on the rails bonded, said nuts being of a hardness exceeding that of steel rails as used in railway tracks, whereby the nuts are capable of enduring without deformation contact with the rails bonded. under pressure adequate to exceed the crushing resistance of iron oxides.

ARTHUR L. LEE. 

